The invention relates to a cover of an internal combustion engine assembly having a common rail, to an engine including such a cover and to an automotive vehicle including such an engine assembly.
The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipments. Although the invention will be described with respect to a truck, the invention is not restricted to this particular vehicle, but may also be used in other automotive vehicles, such as passenger cars, commercial vehicles or construction equipment machines. It can also be used in connection with engine installations used in stationery installations, for example for driving fixed generators or pumps or other fixed equipment.
In the field of internal combustion engines, it is known to have a common rail fuel injection system in order to feed fuel to cylinders. This system comprises pumping element(s) and a common rail or fuel accumulator which feeds fuel to a number of injectors, for example six injectors, each injecting fuel into a cylinder.
The common rail has to be integrated on the engine. Generally, the common rail is located close to the injectors in order to decrease the length of high-pressure pipes connecting the common rail to the injectors. The common rail is also preferably located as close as possible to the pumping elements so that the high-pressure pipes are relatively short.
In a known arrangement, a valve cover, or cylinder head cover, is placed on top of the cylinder head in a fluid tight manner. The injectors, the common rail and the high-pressure pipes are located in the sealed volume defined between the cylinder head and the valve cover.
It is known to locate the common rail inside this sealed volume, so that the potential fuel leakages are contained inside the engine. Consequently, there is no safety risk, but in case of fuel leakage, fuel may be diluted in the oil included in the sealed volume.
Alternatively, the common rail may be located outside the sealed volume, so that the potential fuel leakages do not go in engine oil. However, the fuel leakages may flow down on the road and may also spray in the engine compartment, involving a safety risk.
U.S. Pat. No. 5,533,485 discloses an internal combustion, engine assembly comprising a common rail feeding fuel to injectors. A valve cover defines a closed volume where the injectors are located. The common rail is integrated, partially or completely, in a lateral wall of the valve cover. Pipes for connecting injectors to the common rail pass outside of the valve cover. This design does not allow collecting the fuel leakages due to a failure of such external pipes. Moreover, the maintenance of the common rail requires disassembling the valve cover from the cylinder head and resealing the valve cover on the cylinder head, which is time consuming.
It is desirable to provide means for enclosing the fuel accumulator with a minimum of additional parts, in order to contain fuel leakages and to avoid the dilution of the fuel leakages in the engine oil.
Thanks to an aspect of the invention, the two-piece cover delimitates a closed volume where the common rail, the injectors and the fuel connections between the two are located. Thus, the leakages may be contained in the engine assembly. The cover separates the injectors from the common rail.
The two-piece design of the cover creates two separate sub-volumes with a simplified installation because the fuel connexions between the fuel accumulator and the injector are within the volume and remain attainable during the mounting before the cap is installed to close the volume.
According to further aspects of the invention which are advantageous but not compulsory, such an engine may include one or several of the following features:                The separation wall may comprise an aperture for the passage of the fuel connection from the first sub-volume to the second sub-volume.        The aperture may be entirely formed in a portion of the separation wall pertaining to the frame or may be formed at an interface between the frame and the cap. This allows installing the fuel connection with the cap removed.        The frame may define a first contour bordering the first sub-volume and a second contour bordering the second sub-volume. Those contours may be defined by of beams of the frame.        The cap may include walls defining a first contour coinciding with the first contour of the frame and a second contour coinciding with the second contour of the frame. When the cap is assembled to the frame, the contours match to create the first and second sub-volumes.        A height of at least one beam defining the first contour of the frame may be higher than a height of at least one beam defining the second contour of the frame.        The cap may include a service trap-door opening into the second sub-volume. This allows access to the fuel accumulator without needing to remove neither the cap nor the frame.        The cap may include an integral cover wall.        The cap may include a removable cover wall.        
The invention also relates to an internal combustion engine assembly including a pressurized fuel accumulator feeding fuel to at least one injector, a cylinder head and a cover having any of the preceding features.
The invention also relates, according to an aspect thereof, to an internal combustion engine assembly comprising a pressurized fuel accumulator feeding fuel to at least one injector, a cylinder head and a cover, the cover defining, with the cylinder head, a volume enclosing the common rail and the injector, and the cover bordering a first sub-volume enclosing the injector, and a second sub-volume separated from the first sub-volume by a separation wall of the cover and enclosing the common rail, characterized in that the cover includes a frame fitted on the cylinder head and a cap removably fitted on the frame, and in that a fuel connection connecting the injector to the common rail passes through the separation wall.
Such internal combustion engine assembly may include one or several of the following features:                A sealing element may be located between the cylinder head and the frame.        The separation wall may be extended by an encapsulating element designed to be arranged around the fuel connection, in a configuration where the encapsulating element defines an empty volume around the fuel connection, the empty volume extending the second volume up to a connection zone between a connection port of the injector and the fuel connection.        The connecting element may have the shape of a cylinder having an extremity attached to the connecting port of the injector.        A fuel sensor may be located in the second sub-volume.        A fuel connection may include a pipe having a first portion connected to a connection port of the injector and a terminal portion globally perpendicular to the first portion and connected to the common rail.        
The invention also relates to an automotive vehicle including an internal combustion engine assembly having any of the above features.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.